Adding Envoy gRPC bridge filter example (#78)

examples/grpc-bridge/.gitignore

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+bin/service
+.idea

examples/grpc-bridge/Dockerfile-grpc

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+FROM lyft/envoy:latest
+
+RUN mkdir /var/log/envoy/
+COPY ./bin/service /usr/local/bin/srv
+COPY ./script/grpc_start /etc/grpc_start
+CMD /etc/grpc_start
+

examples/grpc-bridge/Dockerfile-python

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+FROM lyft/envoy:latest
+
+RUN apt-get install -y python-dev
+RUN pip install grpcio requests
+ADD ./client /client
+RUN chmod a+x /client/client.py
+RUN mkdir /var/log/envoy/
+CMD /usr/local/bin/envoy -c /etc/s2s-python-envoy.json

examples/grpc-bridge/README.md

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+# envoy-grpc
+
+This is an example usage of the Envoy [gRPC bridge filter](https://lyft.github.io/envoy/docs/configuration/http_filters/grpc_http1_bridge_filter.html#config-http-filters-grpc-bridge). Included is a gRPC in memory Key/Value store with a Python HTTP client. The Python client makes HTTP/1 requests through the Envoy sidecar process which are upgraded into HTTP/2 gRPC requests. Response trailers are then buffered and sent back to the client as a HTTP/1 header payload.
+
+## Building the Go service
+
+```bash
+script/bootstrap
+script/build
+```
+
+## Docker compose
+
+To run the docker compose file, and set up both the Python and the gRPC containers
+run:
+
+```bash
+docker-compose up --build
+```
+
+## Sending requests to the Key/Value store
+
+```bash
+# set a key
+docker-compose exec python /client/client.py set foo bar
+=> setf foo to bar
+
+# get a key
+docker-compose exec python /client/client.py get foo
+=> bar
+```

examples/grpc-bridge/client/client.py

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+#!/usr/bin/python
+
+import requests, sys
+import kv_pb2 as kv
+from struct import pack
+
+HOST    = "http://localhost:9001"
+HEADERS = {'content-type': 'application/grpc','Host':'grpc'}
+USAGE   = """
+
+envoy-python-client usage:
+  ./client.py set <key> <value> - sets the <key> and <value>
+  ./client.py get <key>         - gets the value for <key>
+  """
+
+class KVClient():
+
+    def get(self, key):
+        r = kv.GetRequest(key=key)
+
+        # Build the gRPC frame
+        data = r.SerializeToString()
+        data = pack('!cI', b'\0', len(data)) + data
+
+        resp = requests.post(HOST + "/kv.KV/Get", data=data, headers=HEADERS)
+
+        return kv.GetResponse().FromString(resp.content[5:])
+
+
+    def set(self, key, value):
+        r = kv.SetRequest(key=key, value=value)
+        data = r.SerializeToString()
+        data = pack('!cI', b'\0', len(data)) + data
+
+        return requests.post(HOST + "/kv.KV/Set", data=data, headers=HEADERS)
+
+def run():
+  if len(sys.argv) == 1:
+    print(USAGE)
+
+    sys.exit(0)
+
+  cmd = sys.argv[1]
+
+  client = KVClient()
+
+  if cmd == "get":
+    # ensure a key was provided
+    if len(sys.argv) != 3:
+      print(USAGE)
+      sys.exit(1)
+
+    # get the key to fetch
+    key = sys.argv[2]
+
+    # send the request to the server
+    response = client.get(key)
+
+    print(response.value)
+    sys.exit(0)
+
+  elif cmd == "set":
+    # ensure a key and value were provided
+    if len(sys.argv) < 4:
+      print(USAGE)
+      sys.exit(1)
+
+    # get the key and the full text of value
+    key = sys.argv[2]
+    value = " ".join(sys.argv[3:])
+
+    # send the request to the server
+    response = client.set(key, value)
+
+    print("setf %s to %s" % (key, value))
+
+if __name__ == '__main__':
+  run()